Radio Age - 1955, April - 36 Pages, 2.8 MB, .PDF - VacuumTubeEra

This Tube Can Translate Code at—
100,000 Words a Minute
NEW ELECTRON-IMAGE tube that can translate
coded signals from tape, keyboard or radio into clearlydefined
letters and figures at speeds up to 100,000 words
per minute for high-speed photographic recording has
been announced by RCA.
The new tube, developed at the David Sarnoff Research
Center of RCA Laboratories at Princeton, N. J.,
fills an acute need for high-speed printing devices
operating directly from data in coded form. When it
achieves commercial form, its initial application is
likely in electronic message transmission and computing
systems. Further development is expected to fit it for
wider application in general printing as an electronic
means of typesetting.
In operation, the tube simulates typesetting in
selecting letters and figures one by one from a "font"
and placing them in luminous form on the 5-inch circular
tube face either in lines or in any pattern desired.
The ability to place the characters where they are
wanted gives the tube wide flexibility for such tasks as
producing financial statements, balance sheets and bills,
where letters and figures must be placed in various
positions on a form.
The "font" from which characters are selected is a
lantern slide bearing a chart of letters and figures which
are projected from outside the tube onto a sensitive
layer at the rear of the tube. Any of a variety of slides
may be used, permitting selection from a wide range
of type styles for reproduction on the tube face.
How the Tube Operates
The new image tube was developed by Warren H.
Bliss and John E. Ruedy under the supervision of C. J.
Young and Dr. G. A. Morton, of the technical staff at
the David Sarnoff Research Center. It is 25 inches long
and resembles in appearance the cathode-ray tubes used
in oscilloscopes. Its operation, however, is substantially
different.
The layer at the rear onto which the slide is projected
consists of photo-emissive material, which emits a
stream of electrons in the pattern of the projected
letters and figures. The electron stream, carrying all of
this information, is accelerated forward in the tube by a
voltage applied to the wall coating of the tube.
The selection of letters and figures in the required
order is accomplished with a tiny aperture at the neck
of the tube, permitting only one character at a time to
The new RCA electron image tube that converts code to
words and figures at high speed is adjusted by Warren
H. Bliss at the David Sarnoff Research Center.
pass through.
As the electron stream moves toward the
aperture, a magnetic deflection coil around the outside
of the tube shifts the stream so that the desired character
passes through the aperture and speeds toward the tube
face. Another set of magnetic coils then focuses and
deflects the character to its proper place on the face,
where it appears in visible form on a phosphor screen
like those used in television picture tubes. As many as
4,000 characters have been produced clearly in a single
pattern on the 5-inch tube face. The second set of coils
is capable, however, of varying the size of the letters
and figures on the screen if enlargements are required.
The entire process of selecting the character, passing
it through the aperture and placing it in the right
location on the tube face can take place at speeds up to
10,000 letters a second, depending upon the rate at which
coded information is fed into the circuits controlling
the tube.
The source of the coded information can be perforated
paper tape, magnetic tape, wire or radio signals,
keyboard selection, or an electronic storage unit such
as a magnetic memory. In tests of the tube at the RCA
Laboratories, the source has been a perforated tape like
those used in teleprinter circuits. In any case, the coded
input can control both the selection of the characters
and their location on the face of the tube.
RAD/O AGE 19